This invention relates to a process for coating the surface of a cellulosic plastic article, and more specifically, to a pretreatment which is performed in this process in order to increase the adhesion of an applied coat.
Generally, the presence of functional groups having high polarity on the surface of a plastic article permits good adhesion of an applied coating. Cellulose inherently possesses many hydroxyl groups which are the highly polar functional groups. In fabrication, however, most of these hydroxyl groups are esterified with, for example, acetic acid, propionic acid or butyric acid to ester groups having lower polarity in order to impart moldability to cellulose. For this reason, the amount of highly polar functional groups present in the surface of a cellulosic plastic molded article is usually small, and without pretreatment, good adhesion is difficult to secure in the coating of such a molded article of cellulosic plastics.